Yes, celebrities cheat more than people in the average population. As a rule, celebrities make much more money than average people. They also usually do a lot to enhance their appearances. Furthermore, celebrities often surround themselves with attractive people. All of these factors taken together would suggest that celebrities cheat a great deal.
I think that celebrities are more likely to cheat than the average population because they are surrounded by so many more temptations than the average person. They are constantly bombarded with fans willing to do anything for a chance to be with them. I think this makes it easier for celebrities to fall into temptation.
When celebrities are discovered to be cheating on their partners, it is inevitably fodder for the gossip magazines and tabloids and for social media users. The effect of this press scrutiny can be enormously disruptive for a person's life. For celebrities, where public image is an essential part of their career, it can also negatively impact them professionally. Therefore, celebrities have more incentive than the average person to be faithful.
People cheat in relationships. It doesn't matter if the couple is famous or not. The only difference between famous couples and couples that are not famous is that when a famous couple gets caught cheating, it becomes news. There are so many famous people, and they don't cheat in any higher numbers than in the general population.